[ReflectImage]

Hello Old Fool, I like the idea of fake bullet hole stickers. It's too bad the photo look pretty straight. Fix it the right way - dig into it - as you say find out and then fix it. But without knowing what was used - we all just shooting in the dark.

[69 widetrack]

Not sure what happened to the thread starter, but thanks for not getting offended.

I don't know about this Ditzler Rep. DP40 is an epoxy and even when it was called DP40 (now it's DP40LF...the LF stands for lead free) should not have needed to be sanded. It should have a 72 hour window before you need to scuff it or open it for mechanical adhesion, anytime in that window and at about 70 degrees you can top coat it without scuffing. I firmly believe that if a vehicle is prepped properly, sealer isn't required.

You mentioned that you chemically stripped the deck lid and dried it...did you rough up the metal with the DA before you put the DP40 on? If you didn't, you could have had some residue left from the chemical stripper that could cause oxidization (same type of reaction as rust) and cause lifting.

Do you remember how long after painting it took for the bubbles to show up? If it was traces of chemical stripper on the panel the reaction would be fairly quick...if it took a while like the thread starter (his took a year and that's why I say it's moisture causing rust) then it wouldn't be the stripper.

The way I would have done the job would be to strip the panel, do my body work, 2 medium wet coats of DP40, let the DP40 flash, 2 to 3 coats of primer, (I would only use 2K primer up until recently), let the primer cure, block sand and paint. I would not have gone bare metal, body work, light coat of DP40, scuff and paint. Did the body work areas ever sink?

Ray

[ReflectImage]

Wow - This is like a assignment, but for austerity I will try to answer your questions. Because we had success we continued to follow the process as I outlined. We only scuff for mechanical adhesion adhering to the 72 hour window. I still have a few bodies that like you say sealing isn't necessary. When we used chemical strippers we always use a DA after to remove any bit and pieces left behind. The rep opinion at that time was - that we may have trapped thinners into the substrates, because the paint at that time was so hot that it burt into the substart and then flash off before the thinners could evaporate. That's why he recommended sealing with a epoxy. The car actually when into storage for quite a long time before taking it to Arizona where it set in the hot sun and broke out covered with bumps. Funny thing when the sun went down the bumps almost disappeared. When we got back to Montana and took down to the metal bit by bit to see what happened and there wasn't any signs of rust. Montana is a fairly dry state and this particular car had very little rust anywhere. After shipping we always DA for mechanical adhesion. It was a complete tear it down take it appart restoration. Prior to using this poly we always used enamel so this was quite the shock. Luckly, we never had this kind of problem again and we continued to poly paint. Thanks for you input hope this answers your questions.

[69 widetrack]

Wow, your right...this is an assignment. I still say that the Rep was wrong...sorry, I'll try and explain why. If the paint was so hot and the paint flashed over before the thinner could evaporate it wouldn't blister, it would solvent pop...and the fact that it almost went away when the sun went down tells me it's not thinner, it's expanded air...one way to get air to expand is by oxidization or off gassing and it doesn't take much oxidization to create a gas between metal and paint. Even if you trapped thinner, how would putting DP40 over top seal it and stop the bubbles? Because it was so hot, could it be tiny bits of water vapor from the compressor?

This may need to go on "Unsolved Mystery's"...LOL...but I can't see it being trapped thinner...that would cause a pop, not a blister...I could see it being moisture from an over heated compressor...not droplets...atomized moisture going through the paint gun.

One more stupid question... did you go, bare metal, body work, DP40, paint or bare metal, DP40, body work, primer, DP40, paint...Or how did you guys do it back then?

[ReflectImage]

Forgot to answer the sink question: No, this was a perfect deck lid needing very little bodywork or fillers.

[ReflectImage]

Bare metal, DA, DP40, bodywork, primer, DP40 thinned down, scuff for mechanical adhesion, then paint. We always strived for concourse restorations through out the years. One of our cars was judged 99.99. This has been a interesting discussion - time for my night cap - have to get up early. Goodnight.

[deadbodyman]

Originally Posted by Old Fool

Apparently the OP does not want to tell how he prepped and painted the car to figure the problem out.

Doesn't look like he even returned to the post?

He could shave the surface off and see what is under there, a careful shave cut and one of those fake bullet hole stickers and he would be set <jk>

My hunch is acid wash primer or similar as the original cause. But I am not a gambling man, so I wouldn't put any money on my hunch,LOL.

I'm thinking a drop of sweat landed on the bare metal, no wax & grease remover,along with thick material...or an air bubble in the filler...If it was moisture there would be lots of tiny bubbles not a big one here and there. Its anyones guess...it looks like a lot of time went into it though...
Mabee the OP used lacquer primer..and was too embarresed to come back...

[ReflectImage]

As to the OP Question: If he did everything according to Hoyle, then it could be, like Deadbodyman suggested a couple drops of sweat or wrong primer.

For the our situation with the deck lid and dozens of small bumps: I think the only answer is to put it in the Archives under "Unsolved Mystery's" & "Lesson Learned". Having said this, I seemed to remember the reason we continued to use one light coat of DP40 thinned down, under the paint. If not for insurance against chemical burn-in,....then because we noticed that the polyurethane seemed to lay down flatter and smoother. It might not behave the same now that the lead is gone. This was our hobby - turned restoration pro and made our living for twenty-some years.

Glad DP40 no longer has lead in it,...this is one hazard of the trade, that needed to be gone.
Reflections

[69 widetrack]

Originally Posted by ReflectImage

As to the OP Question: If he did everything according to Hoyle, then it could be, like Deadbodyman suggested a couple drops of sweat or wrong primer.

For the our situation with the deck lid and dozens of small bumps: I think the only answer is to put it in the Archives under "Unsolved Mystery's" & "Lesson Learned". Having said this, I seemed to remember the reason we continued to use one light coat of DP40 thinned down, under the paint. If not for insurance against chemical burn-in,....then because we noticed that the polyurethane seemed to lay down flatter and smoother. It might not behave the same now that the lead is gone. This was our hobby - turned restoration pro and made our living for twenty-some years.

Glad DP40 no longer has lead in it,...this is one hazard of the trade, that needed to be gone.
Reflections

I agree, unsolved mystery's it is.

Your right about the DP40 and the lead content...it was deadly...but, ever since they took the lead out, it wasn't quite the same product...just like Centauri from Dupont...when they took the lead out of that Acrylic Enamel it never seemed to cover as well (if I remember correctly yellows where a real bear to get coverage on after they took the lead out) or shine as much and the durability seemed to drop of as well.

But that's old school paint and water under the bridge.

Ray